I am currently working on the spider exercise as well.

When I was just practising with the first 3 fingers as Lisa recommends initially I had a similar problem to you.

I decided to try adding the pinky to the exercise to try and train that along with the others and it seems to be working.

The other problem I found was keeping the other fingers fairly close together and near the fretboard, which Lisa said might be a problem. That seems to be coming together as well now.

I plan on practicing that exercise about 30 mins each day for a week before doing next lesson so hopefully I should have it reasonably down, ready for next steps.

Stick with it 😊