Try this:
tct@ub16:~/openvpn/windows$ wget https://swupdate.openvpn.net/community/keys/security-key-2018.asc
--2018-07-13 15:41:17-- https://swupdate.openvpn.net/community/keys/security-key-2018.asc
Resolving swupdate.openvpn.net (swupdate.openvpn.net)... 104.20.194.50, 104.20.195.50
Connecting to swupdate.openvpn.net (swupdate.openvpn.net)|104.20.194.50|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 21168 (21K) [text/plain]
Saving to: ‘security-key-2018.asc’
security-key-2018.asc 100%[==================================================================================>] 20.67K --.-KB/s in 0.06s
2018-07-13 15:41:33 (354 KB/s) - ‘security-key-2018.asc’ saved [21168/21168]
tct@ub16:~/openvpn/windows$ wget https://swupdate.openvpn.org/community/releases/openvpn-install-2.4.6-I602.exe
--2018-07-13 15:41:41-- https://swupdate.openvpn.org/community/releases/openvpn-install-2.4.6-I602.exe
Resolving swupdate.openvpn.org (swupdate.openvpn.org)... 104.18.252.114, 104.18.248.114, 104.18.251.114, ...
Connecting to swupdate.openvpn.org (swupdate.openvpn.org)|104.18.252.114|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3861232 (3.7M) [application/x-ms-dos-executable]
Saving to: ‘openvpn-install-2.4.6-I602.exe’
openvpn-install-2.4.6-I602.exe 100%[==================================================================================>] 3.68M 182KB/s in 20s
2018-07-13 15:42:11 (191 KB/s) - ‘openvpn-install-2.4.6-I602.exe’ saved [3861232/3861232]
tct@ub16:~/openvpn/windows$ wget https://swupdate.openvpn.org/community/releases/openvpn-install-2.4.6-I602.exe.asc
--2018-07-13 15:42:17-- https://swupdate.openvpn.org/community/releases/openvpn-install-2.4.6-I602.exe.asc
Resolving swupdate.openvpn.org (swupdate.openvpn.org)... 104.18.252.114, 104.18.248.114, 104.18.251.114, ...
Connecting to swupdate.openvpn.org (swupdate.openvpn.org)|104.18.252.114|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 833 [text/plain]
Saving to: ‘openvpn-install-2.4.6-I602.exe.asc’
openvpn-install-2.4.6-I602.exe.asc 100%[==================================================================================>] 833 --.-KB/s in 0.002s
2018-07-13 15:42:22 (338 KB/s) - ‘openvpn-install-2.4.6-I602.exe.asc’ saved [833/833]
tct@ub16:~/openvpn/windows$ gpg --import security-key-2018.asc
gpg: directory `/home/tct/.gnupg' created
gpg: new configuration file `/home/tct/.gnupg/gpg.conf' created
gpg: WARNING: options in `/home/tct/.gnupg/gpg.conf' are not yet active during this run
gpg: keyring `/home/tct/.gnupg/secring.gpg' created
gpg: keyring `/home/tct/.gnupg/pubring.gpg' created
gpg: /home/tct/.gnupg/trustdb.gpg: trustdb created
gpg: key 2F2B01E7: public key "OpenVPN - Security Mailing List <security@openvpn.net>" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
gpg: no ultimately trusted keys found
tct@ub16:~/openvpn/windows$ gpg -v --verify openvpn-install-2.4.6-I602.exe.asc openvpn-install-2.4.6-I602.exe
gpg: Signature made Thu 26 Apr 2018 18:10:49 BST using RSA key ID AF131CAE
gpg: NOTE: signature key 8CC2B034 expired Tue 06 Mar 2018 12:17:50 GMT
gpg: using subkey AF131CAE instead of primary key 2F2B01E7
gpg: NOTE: signature key 8CC2B034 expired Tue 06 Mar 2018 12:17:50 GMT
gpg: using PGP trust model
gpg: Good signature from "OpenVPN - Security Mailing List <security@openvpn.net>"
gpg: NOTE: signature key 8CC2B034 expired Tue 06 Mar 2018 12:17:50 GMT
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: F554 A368 7412 CFFE BDEF E0A3 12F5 F7B4 2F2B 01E7
Subkey fingerprint: D518 B9BD 643C F94D A5ED 9970 F132 B1CB AF13 1CAE
gpg: binary signature, digest algorithm SHA256
tct@ub16:~/openvpn/windows$ gpg --version
gpg (GnuPG) 1.4.20
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Home: ~/.gnupg
Supported algorithms:
Pubkey: RSA, RSA-E, RSA-S, ELG-E, DSA
Cypher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2
