Returning triathlete after 15 years off

Turned 49 this year, decided to return to the lifestyle that being a triathlete affords. However doing so at a much older age, and after 2 shoulder surgeries and a spinal fusion. thus, uncertain how far I can push my body so starting off slow.

Signed up for my first sprint tri August 19th in Georgia.

Was excited to return to BT.com, found a beginner plan, and paid for Bronze membership so that I can import into my calendar.

Unfortunately when I went to install the BT app on my android phone, I could not do so b/c it said it was created with an older version of android.

Now I'm concerned BT has not kept up with the times and wondering what others experiences have been. Being unable to utilize my phone with an app is a pretty big disappointment. Please provide your feedback on what your experience has been and how you've overcome this limitation, if you have.

Thanks in advance.