Microsoft on-premises server product that runs Office Online.
This looks like a front-end bug, I found a work-around that is a pain, but is working as of 01-09-2024
• Go to dev panel, click set up e5 sub
• Error pops up
• Close error
• Click settings cog
• Navigate back to the dev panel
• Set up E5 sub pops up
• Completed info, got another error
• Closed error again
• Navigate to settings cog again
• Navigate back to dev panel
• E5 dev env successfully set up.
I can't help but to laugh. But it worked :)