Category
Where open and closed tickets live and what happens when a category is full.
Ticket channels live in Discord categories. This group decides which ones.
#Opened category
New tickets are created here. Without a category, tickets appear at the top of the channel list, which most servers do not want.
#Closed category
When a ticket closes, it moves here. Leave it empty to keep closed tickets where they are. A separate category keeps the list of open tickets short.
#Overflow categories
Discord allows 50 channels per category. When the opened category is full, the bot uses the overflow categories in the order you set them. You can add up to 25. If every category is full, the member gets a short message that asks the team to add one.
Overflow categories count towards the Discord limit of 500 channels per server too. Delete old tickets regularly, by hand or with an automation.
#Permissions of the category
The bot sets its own permission overwrites on every ticket channel, so the permissions of the category do not leak into tickets. It still needs View Channel and Manage Channels in the category itself. If a category is private, give the bot's role access to it.