a quick search on the altstore discord for Linux returns this. By locked, this usually just means password reset to iCloud. This happened to someone recently trying a tool called sideloadly on mac, I never had an issue like this with the official altstore build, is why I feel comfortable recommending it. This is in return to “in a docker container” and not the alternative build. Wether this alt-alt build address that or not idk.

the .ipa file will work with any working sideload method tho. Others who are comfortable and been running sideloadly report it works fine.