There are two different route types (admin and content-api). API tokens and U&P only work on content-api routes, not admin.
You can create content-api routes from your custom plugin with the following syntax:
const contentAPIRoutes = require('./content-api');
const routes = {
'content-api': {
type: 'content-api',
routes: contentAPIRoutes,
},
};
module.exports = routes;