Can you start treatment without going to the clinic to have the attachments fitted?

It's important to schedule a fitting appointment if you need attachments, here's why

In order to get the best start and outcome from your clear aligners, it may be necessary to visit an orthodontist at the clinic for attachment fitting or interproximal reduction, before wearing your aligners.

In either of those cases, you must go to the clinic to have these pre-treatment procedures done by the orthodontist.