discord-akairo | A bot framework for Discord.js | Chat library

Discord-Akairo appears to be currently in the process of upgrading to discord.js v13, as you can see on their Github. To use that framework with discord.js v13.x, you'll just need to wait for them to release their next update.

Unless you are confident and knowledgeable enough to fork their repository, and edit the framework to work with v13 yourself. That would have the added advantage of being able to further customize the framework to your needs.

The reason you're getting the "client.setInterval is not a function" error is because Discord.js removed that method in v13. On top of that issue, extendable structures were removed, and there are hundreds of other breaking changes that would make it impossible to use the current version of Discord-Akairo with djs v13.

For now, unless you choose to fork Akairo, you'll need to downgrade to discord.js v12.x, as you've already done. It should work for now, but you will of course be missing out on many of the new Discord features such as threads, buttons, select menus, and slash commands.

You may also want to consider using a different framework that already has v13 support for now, perhaps some sort of similar framework so you can easily transfer back to Akairo later if you so choose.