Problems linking my OV-chipkaart to my NS account

I solved it by changing my address to that of the Hotel in which I am staying and the site let me complete the payment. My question is, are there any problems with declaring a "fictitious" address since I don't have my residence here?

Not really, if there is no card to be sent to that address. You can change the address back to your residential address later via https://www.ns.nl/en/mijnns#/persoonsgegevens

You'll need to change it to a Dutch address every time you want to change the subscription.

When in need, temporarily change it to 3511 ER house number 100 (Laan van Puntenburg Utrecht, NS headquarters). Phone number can be 0100000000 (any 10-digit number starting with 0), mobile number can be empty.

The Focum credit check is a hassle, because it also checks for other debts in your area/postcode.

Thank you for your replies but I simply solved it by changing the address to that of my hotel (and I hope it won't be a problem for the train inspectors).

One last thing, confirm me if I understood correctly:
1. I have activated NS Dal Voordeel (which I need to collect at the machine) - now all journeys by train/bus/tram/metro/bike will be directly debited from the bank account with which I paid via iDeal when subscribing to the pass, is it right?
2. I have activated the automatic reloading of the OV-chipkaart - I assume it is useless since a minimum balance is not required to travel with NS Flex - do you recommend disabling it? Since my balance is 0, I'm afraid that the system will upload money to the OV-chipkaart but then the transport costs will be debited from my bank account and not via the money loaded on the card.

We will charge all trips by public transport monthly and debit them from the IBAN you used to pay with by subscriping for NS Flex. We will switch off automatic loading for you when you change to NS Flex.

When activating NS Flex at a machine, the following happens:

1. Automatic reloading is disabled (needed to remove the balance from the card)
2. Any balance is removed from the card, you will get this back on your next monthly invoice
3. The product Reizen op Rekening NS trein (this is NS Flex) is loaded on the card
4. (optionally) Reizen op Rekening NS bus tram metro is loaded on the card

The BTM (bus tram metro) product is typically loaded, but if you have a subscription for e.g. buses it may be omitted (or removed upon request), because NS Flex can’t handle the subscription and will always charge full fare for BTM. In that case, you need balance and may want to re-activate the automatic reloading because with NS Flex you can’t load balance at NS machines anymore.