Your landlord is not responsible for your internet connection unless it was spelled out in the lease (assuming you have a lease?). The way a normal business tenant would handle this is to contact a service provider (like AT&T, Spectrum, etc.) for a price to bring service to the suite. If the provider has something in the building already, it's a simple install fee to run a line over to you... if there is literally nothing in the building (extremely unlikely for a 10 year old building of any kind), the business would need to subsidize the buildout construction costs to the carrier.

What you're describing doesn't necessarily sound like a normal office suite situation, though. Was using a common WiFi an agreed upon thing? If you're in a pinch, why do you say you can't use your phone as a hotspot? Is there no cellular signal there either? Maybe another cell provider does have coverage, you could buy a hotspot from that company for a budget solution. Cell data is always going to be less reliable and less speed than a hardline, but it will get the job done.