Esa - first time applying

New style esa, first time applied and finally 2 weeks on had first phone call yesterday. I have pip but esa is all new to me, i have had to leave employment due to worsening conditions. My doctor has initially signed me off for 3 months and I have lots of consultants letters detailing my limitations, double incontinence etc. Question- i thought the call was a formality 'your in the system a questionnaire will be on its way eventually', but he started asking can you volunteer for 16 hours? I offered to send in consultants letters and explained a little, also having no sleep due to new cpap machine and cfs and he said eventually said no problem I have put you as no requirements for 4 months - but what does this actually mean?
It seems so much more complicated than the gov website suggested, surely they at somepoint look at your medical notes?
Any help greatly appreciated, sorry for the ramble

Thank you for explaining, it does seem very strange. It's my first ever experience with contact from the job centre. I will start to work through the esa guide pre my pip renewal also.