How is it serving as an 11B who requires a CPAP machine? How does that affects your career?

It won't affect your career. You won't die without a CPAP in the field, you'll just be a loud sleeper like you were before. Lots of people in the Army sound like a tractor trailer downshifting while speeding down the Smokey Mountains when they sleep. On the positive (maybe?) side it will usually count toward your VA disability rating when you retire.

Bottom line, unless you can't live (will die) without it, it won't affect your career. Unless someone smothers you in your sleep.

When I was in and still an 11B I used a CPAP. The PA put a referral for an external battery I can’t remember if I go 1 or 2 but they power your CPAP for deployment and FTX.

In 1998 I was diagnosed with Narcolepsy with Cataplexy, basically meaning I could fall asleep uncontrollably, with sudden loud noises could put me in a sleep like state. This was all after several years of service with zero asleep on duty incidents. I was told at that time if I needed a CPAP I would still be deployable, but if I needed a Bi Pap I would be considered undeployable and be removed from Military service. When it turned out to be Narcolepsy they met boarded me and sent me packing. When I went for my VA evaluation, they said it wasn't Narcolepsy, it was Sleep Apnea which required a BiPap so I was still out of service. Later I was a Government contractor and was trying to go overseas to support the war effort, and was told unless I could aquire a machine that used batteries instead of electricity I would not be allowed to deploy.