So you just have to go to your series, copy the link in the internet text box (the URL of that internet page) then paste that link in your messages. You could also go to edit your series and copy the unique link tapas gave your series from there and then paste it in your messages. This link should be in a text box that has the URL symbol next to it.
Also make sure the link isn’t spaced away from the border of the message so that the preview can come up like all the other links. For example,
With space away from the message’s left border:
https://m.tapas.io/episode/3306431
https://m.tapas.io/episode/3306431
Versus the link without space between the leftmost border and itself:
If you have any more questions pls post them. I hope this helps. @LadyMnM
P.S. just found your novel so I subbed. I also got the link so I’ll also post it in a couple threads to help with your promotion if you don’t mind.