In addition to the PPPoE username and password, you probably have to change the PPPoE settings for it to work. Do what TXSim suggested and do a reset of the router first.

Then, when setting up the router again for TIME, there should be a setting somewhere BEFORE you put in the username and password where you have to specify the PPPoE settings to be used. It should be drop-down menu somewhere where you can select 'Unifi Home' (which is probably what it was set to before), 'Unifi Biz', 'Maxis Home', etc. There should be one for 'TIME' somewhere, since I seem to remember that the Archer C7 has a fat 'TIME Fibre Broadband compatible' sticker on the box at the shops.

Since you were using your TPlink with unifi previously, your router is still probably using unifi profile with vlan tagging. You need to unselect this feature to use the router with TIME.

You don't need to setup VLAN for TIME. Go to "Quick Setup", you should see following options, choose Normal mode and then continue with the rest of setup process.

Normal Mode - You don't have applied any IPTV or VOIP service
Unifi Mode - You have applied TM Unifi service
Maxis Mode - You have applied Maxis Fiber service
Other Mode - You have applied some other ISP's service which should be configured with VLAN information.

Then go to Network -> WAN and setup as follow:
WAN Connection Type: PPPoE/Russia PPPoE
Secondary Connection: Disabled
Wan Connection Mode: Connect Automatically

Last time when I wanted to buy router also consider c9 but due to its looks I decided not to. The c7/c5 looks is better and the ac5400 and ad7200 also have better looks. The 2600 and 3150 just urgh. Both of the routers u ask support TIME.