https://www.philips.co.uk/c-p/346B1C_00/curved-ultrawide-lcd-monitor-with-usb-c
That monitor has USB-C (DisplayPort, USB), DisplayPort, and HDMI inputs. It is not a Thunderbolt monitor.
Apple does not make a USB-C to Thunderbolt 2 adapter. They make a Thunderbolt 3-to-2 adapter, which has a USB-C plug on the Thunderbolt 3 side, because Thunderbolt is one protocol that can live on a USB-C connector. That adapter is bi-directional but only translates Thunderbolt protocol. It will not generate a USB-C (DisplayPort) signal on the Thunderbolt 3 side, of the sort that the Phillips 346B1c/00 is expecting. It also will not carry power from one side to the other – just Thunderbolt-format data.
If someone told you to use that adapter for connecting that monitor, they don't know what they're talking about.
I don't know, offhand, of any Thunderbolt 2 to USB-C (DisplayPort, USB, USB Power Delivery) adapters that will do what you want. I think that you're looking at several cables:
- A Mini DisplayPort to DisplayPort cable, running from the Thunderbolt 2 port on your 2015 MBP (which has a Mini DisplayPort connector, and can double as a Mini DisplayPort), to the DisplayPort input on the monitor.
- A USB-A to USB-B cable, running from one of your 2015 MBP's USB-A (USB 3) ports to the upstream USB-B port on the monitor.
- A MagSafe 2 cable running from your 2015 MBP's MagSafe 2 charging port to your Apple power adapter.