Manager Insisting To Come In Early But Not Paying For It, When I Didn’t Follow He Questioned/ Confronted Me About It.

Hi guys, I am 22F working in hospitality in Canada.
Location: British Columbia, Canada.
I work the front desk and usually come in at the exact second my shift starts.

I live on site, basically working in a resort/ hotel and living there as well so my work commute is less than one minute. If I am scheduled to work at 3 pm I leave at 2:58 and arrive at work by 2:59 or 3:00.

Recently our manager left a message in our work group chat -

“ Hi everyone, please come downstairs 10 minutes before your shift starts. It usually takes about 10–15 minutes to get settled and be ready to begin work, so arriving a little early helps ensure your shift starts on time. Thank you for your cooperation!”

So, I asked him in person to clarify if he wants me to start 10 - 15 minutes early and will I be payed for it?
He said that he does not want me to actually work but just be in the lobby, I can look around and analyze stuff and this step is basically just to get the staff in work zone before the work actually starts.

I said okay and figured this is optional, I still came in at 3:00 exact, the next day. As soon as I come in my manager saw the camera and texted me that he asked me to come in at 2:50 and I must take it seriously.

So someone else is supposed to cover the desk till 3pm and that person also handles other tasks in the back end. Whenever there’s no guest to attend at the desk that staff member goes back in to finish the other tasks.

So, the next day I actually come in at 2:50 and a guest walks in right away. We make eye contact, I greet the guest and ask them to wait for help the staff will assist them shortly.

I am technically supposed to start attending guests at 3:00 pm right? So if someone comes in before that it’s not even my responsibility to greet them but i still did and rang the service bell to notify the person on shift.

My manager comes in next day and talks to me in very confronting manner, asked me why didn’t I serve the guest? Why did I make them wait if I was right there?

Can someone advise me what is right and what is wrong here? Should i say something to them? Start coming in at 3:00? Or clock in at 2:50 if i have to provide my services before my scheduled time? Or should i just do it for free for them? Should I quit?
Am I just overreacting and overthinking the situation?