Build its own credential : how to set Nodes allowed to use it?

I can see that MySQL node can be allowed in the mysql credentials form
But I can’t see this in the mysql credentials source
So how can I allow a custom node to use my custom credentials ?

You have to define on the custom node that it wants to use the “mySql” credentials:

Then the custom node will show up in that list and you can give it access.

Thanks jan, it works, I didn’t use the good name of my credential.