Hello,
Happy to try to help you get these things resolved. 
Letâs start with the Textbook field first:
If you donât already have it installed, the AnKing Note Types add-on makes adjustments like this a lot easier so I would recommend using it (assuming you donât already have it). The add-on page is here (https://ankiweb.net/shared/info/952691989) though if youâre familiar enough with installing an add-on the code is thus: 952691989
You can install the add-on within Anki by going to your top menu bar, clicking on Tools - Add-ons - Get Add-ons, and inserting this code. Once itâs installed youâll want to restart Anki.
From there, once youâve restarted Anki you should see âAnKingâ on your top menu bar, like so:
Clicking âAnKing Note Typesâ should lead you to a screen like this:
Under the âFontâ tab there should be an option to âauto revealâ individual fields in the note (I used a different field as an example here since I donât have the Ankisthesia deck, or note type, installed, but the basic process should be the same) :
And then we can move on to the images themselves:
I havenât used that deck personally so Iâm not quite as intimately acquainted with it but a quick glance at the deck landing page seems to indicate that the textbook images are hosted separately:
If you click on the âView on Communityâ link from that deck landing page, it appears that at least one person in the comments has linked to what looks like an externally-hosted media folder, which might do the trick:
[Wiki] Ankisthesia by Ankisthesia - #13 by anking.jacobâŚ
Give those things a shot and let me know how you fare, and weâll go from there.