The facility is not going to deliver that information for you. Staff are not in the business of passing phone numbers from outside parties to inmates, and while occasionally an empathetic officer will make an exception, that is not something you can count on or plan around.
The reliable way to get the number to her is through mail. Send a letter or postcard to Gilpin County Detention Center with the InmateAid number written clearly inside. That piece of mail will go through the normal intake and delivery process and she will have the number in hand once it arrives.
InmateAid's letter service is the most straightforward way to do this. You can send a letter directly through the platform and it will go out via USPS, typically arriving within two to three days of processing. A postcard works just as well for something this simple and gets the job done without needing to write a full letter.
Once she has the number she will need to submit it to be added to her approved call list at the facility. That process varies slightly by facility but generally takes a few additional days to process through the phone carrier. From the time you send the letter to the time she can actually dial the number and have it go through, budget about a week to ten days total to be safe.
If you want to confirm everything is set up correctly on the InmateAid end before you send the number, reach out to aid@inmateaid.com and the team can verify the account is active and ready.