[Q] Deciding the best regression analysis for a dataset

Hi everyone. I have a dataset and wanted some feedback on the proper analysis. It’s a repeated-measures design with 5 continuous variable observations per subject. For example, a score on a test and a self-report Likert scale of anxiety, both collected for each observation. I want to see if a continuous trait variable predicts the strength of the correlation between the test score and reported anxiety.

The following link is close to what I want to do, but instead of two groups, it’s a continuous variable. I’m basically trying to run a regression between a trait score and a bunch of correlations coefficients . Can anyone offer any guidance here?