Take pictures of the documents on your phone. Write an email on your phone to yourself and attach the documents. You will be asked what size the photos to be. Choose small size less than 5 megabytes.
Open the email on your computer and download the pictures. Give each one a name of what it is…passport, bank, vaccination, insurance etc.
These will be small enough you can upload them to the embassy website application form.
I have done this for 6 Thailand Pass applications for myself and friends.