Hi, @jg2313
I believe that you are seeing something like this on your end:
Since the log snippet is complaining about i/o timeout, can you please confirm the connectivity of your Mattermost Server to the Marketplace by running the echo | telnet api.integrations.mattermost.com 443? You would see something that looks like this:
ahmaddanial@mattermost:~$ echo | telnet api.integrations.mattermost.com 443
Trying 65.8.113.91...
Connected to api.integrations.mattermost.com.
Escape character is '^]'.
Connection closed by foreign host.
Can you also confirm that you have configured the ownership of the files in the /opt/mattermost directory to be under the mattermost user?
If not, please run the sudo chown -R mattermost:mattermost /opt/mattermost/ and reload the Marketplace again. Let me know how it goes.