It's rather simple to be honest.
You must have one physical "face-to-face" meeting with the Doctor. So, this means at least one trip (drive or fly) to see the Physician in question.
When you meet the Physician they will have you fill out a bunch of paper work, the will conduct a Physical Exam conducive to a man wanting to start a TRT protocol and they will draw blood.
After that, everything is done via a phone call or webinar of some form...think of it as a virtual Doctor's office visit.
Ongoing, the Doctor will order blood work for you that will be sent to his office for review and to make any adjustments to your protocol.
Some Doctor's do require you to meet with them on an annual basis so if you have to fly to drive far that needs to be in your consideration as well.