I am hoping to adapt some of the CREDI items so that they are more targeted to my specific population.  Is that ok?

No. The CREDI Short Form and the CREDI Long Form have been validated as scales that are designed to be use exactly as they are written.  You should not adapt the items or change them in any way unless absolutely necessary (see Adaptation & Translation section of the CREDI User Guide). If you want to add more items that are specifically relevant to your population, you may create your own items or borrow them from another tool. If you choose to do this, you should still score the CREDI using only the items in the original Short or Long Form based on the instructions provided in the CREDI Data Management and Scoring Manual. If you want to integrate your additional items into your scores, you will need to validate your new scale on your own and be clear in publishing about the changes you have made.