From searching on "missing token" in the Help forum, I found this thread:
Including Images and Attachments (as of 24 Jan 2020)
For the file size issue, I have that myself. I have an old school digital camera and although I have updated the software as much as I can, I have no easy way to decrease file size. Although the text says "5 MB" that is the total for each attachment. Try more for around 1 each.
I use this site -- I have no connection other than I use it because it is very quick, very easy and does not set off my browswer protection warnings:
https://www.reduceimages.com/
Drag your image onto the box (from your camera or file manger), click on their defaults and download the image.
Come here, I choose the Go Advanced option (have not been able to get the paper clip to work for me but I think that is because of my browser protections) and upload the image -- remembering (which I still forget about half the time) to enlarge the window so you can see the Upload button to the far upper right.