I want to transfer about 75Mb of photos from my iPhone XS to my iMac. Unfortunately my iMac can't run a later Mac OS than High Sierra, so Airdrop doesn't work. An alternative is to set up an email of a bunch of photos and then agree to them being sent via mail drop to iCloud. I have set the appropriate preferences in my iCloud account, but the pictures never appear(in fact it isn't too clear where they are supposed to appear, since this isn't stated in the instructions, but I assume somewhere on my iCloud Drive). I don't get any indication that the photos are being sent or received either from the phone or the iMac.
What am I doing wrong?