rna2star
I'd suggest using a thumb drive + the USB-C adapter that you got with your phone.
Copy your backup files to your thumb drive, then copy the files from the thumb drive to a folder called WhatsApp
(in the root of your user/profile directory, the same folder with Pictures
and Downloads
)
Before launching WhatsApp, give it access to that folder using storage scopes. Go to Settings > Apps > All Apps > WhatsApp > Storage Scopes. If you don't see Storage Scopes, go to WhatsApp > Permissions > Photos and videos > configure storage scopes > turn on storage scopes. From there, tap "add folder" and navigate to the WhatsApp
folder, open it, then tap "choose folder" at the bottom.
Next, launch WhatsApp and follow the steps on WhatsApp's website for restoring a local backup: https://faq.whatsapp.com/618575946635920/?cms_platform=android
I've never done this before, so hopefully this works for you!