12 weeks ago by
I found this prior Q&A that sounds like it might be your problem as well: https://biostar.usegalaxy.org/p/8548/
I am not sure how the other user was able to access the admin tools if not actually an admin in the configuration files, but when they cleared that up and importantly, restarted Galaxy, that resolved tool installation problems that sound very similar to yours. To have an account be an "admin" account, the galaxy.ini/yml file needs to be adjusted (add email to list of admins) and Galaxy restarted for that to take full effect. Then when later logging into a GUI registered account using the same email address, tool installation should work. The GUI account can be created before or after the ini/yml change and restart.
Please give that a try, and if it doesn't resolve your issue, then comment back with the Trinity repository link and let us know if this is the only tool that you cannot install, or if it is all tools, and if this is new behavior or something that started after other changes to the server were made (what changes?). The version of Galaxy you are running would also be helpful to know.
Thanks! Jen, Galaxy team