I don't know if it's safe or not, but it's not in Paris. It's outside the périphérique, to the north northwest of the flea market.

Well, first of all Saint Ouen is a suburb -- it is not in Paris.

However, that street is quite close to the Porte de Clignancourt metro station at the end of metro line 4, so it should not be a problem. Nevertheless, unless the apartment is the deal of the century, it is quite possible that you will be disappointed with the location and the travel time into the center of Paris.

For areas within Paris the last two number of the mailing code will be between 01 and 20.

I don't know what the area is like but my questions would be:

How safe is it - esp coming home at night?

How far is the apartment from the nearest Metro station? And how long will it take to get into the center of Paris?

What shops and services are in the immediate vicinity of the apartment - since presumably you are planning to cook in to save money.

To further to NYs post, the zip code for Paris must start with 750,, then is followed with numbers 01-20.
Your hotel is not in Paris at all, so you will likely pay more for transport in and out each day, which may add up for so many people.
I think I would try to find a place inside Paris, and I suggest you post a question here asking for ideas,and please include what you would like to be pay per night.

For areas within Paris the last two number of the mailing code will be between 01 and 20.

the beginning numbers--75--are a better indication as they represent Paris as distinct from the suburbs. Note that this postal code 30120 in the Gard ends with 20.

The inner suburbs (of which St-Ouen is a part since it touches Paris) are numbered 92-93-94 which explains the postal code of 93400.

Have you looked up the address and "walked" around the neighborhood? That would give you some idea of the area. When I googled it, this listing came up on airbnb: https://www.airbnb.com/rooms/804855. Is that the apartment you're looking at? I noticed it had no reviews, so be cautious.