Meldeverfahren permit... how does it go?

What is the correct way to do the max. 3 month residency for working? As an EU citizen I have the right to work up to 3 months in Switzerland with the online form where I state that I start working. I would just live in my gf`s apartment but not make it official on the rent as I will leave and also I do not need to pay health insurance for this time, so not sure how a rental paper would change that.

When I do the online form and need to give an address, is there a problem with the current landlord/agency or I just need to submit it to the city council?

Are you self-employed or being posted here by your employer?

I would be employed by a company

Who has to submit a notification form?
The following categories of individuals are authorised to work in Switzerland for up to three months or 90 days per calendar year by virtue of the notification procedure:

EU/EFTA nationals who have been employed to work in Switzerland by a company based in Switzerland for a period of up to three months.
Posted workers from a company based in an EU/EFTA member state, regardless of this worker’s citizenship. Third-state nationals, however, must have been admitted permanently in a labour market of an EU/EFTA member state before being sent to Switzerland. Generally speaking, this criterion is deemed to have been met if the individual has held a standard or permanent residence permit in that country for at least twelve months.
Self-employed service providers (EU/EFTA nationals) based in an EU/EFTA member state.
The notification form is submitted by the employer of posted workers and of EU/EFTA nationals who have found employment in Switzerland. Self-employed service providers must submit this notification form themselves.

https://www.sem.admin.ch/sem/en/home…ml#-1597848948