You need a hosting site and the resolution UKBEG will accept is low, something like 600 pixels wide max.
I've never had problems putting pics on UKBEG, 5mb is the biggest I can put on but I always cut off some of the inconsequential background just to keep them smaller.
I do have a camera though & copy the pics onto my computer first as I know what I'm doing that way.
I only use my phone if I'm using Whatsapp to send, (great for videos as well).
I'm guessing a hosting site is the same as a folder on your computer? Although more complicated which I find normal for technology, it's rarely easier the more tech you put in between I find.
I just click on add photo & tell it where to find it, really easy.
Hope everyone's well & enjoying the sunshine