McDowell was arrested early Sunday morning in Atlanta, GA after a cop says she saw him getting into a verbal altercation outside the front doors of a club called SL Lounge.

According to the incident report, obtained by TMZ Sports, McDowell was shouting at the head of security about $600 he believed he'd already paid ... even though he was repeatedly told by staff and his own friend he hadn't given them the cash he wanted back.

He was eventually allowed back in ... but the arresting officer says he was kicked out again ... still shouting about the money, and refusing to leave without it. The cop says she was told McDowell poured out a couple bottles of liquor inside and got booted.

During a profanity-laced tirade, the officer says she detained McDowell with the help of her partner. They tried getting him in the back of their patrol car when he allegedly said ... "F*** both of ya'll hoe ass n*****, p**** ass cops, I bet I get out, I got more money than ya'll, ya'll ain't got enough money for me, p**** ass crackers, broke ass n*****."

The arresting officer says she had to almost tase and pepper spray McDowell when he refused to comply with her orders, but adds she ultimately didn't use either.

He was booked for disorderly conduct, and was released on a $325 bond. McDowell suffered a concussion this summer and is not on the active Seahawks roster.