Only one project can be created?

only one project can be created? why and how todo?

are you referring to the cloud version or the on-premise version? For the cloud version you can create as many projects as you want. For the on-premise version instead if you use the community version you can create only one project otherwise you have to buy the Tiledesk on-premise Enterprise version
Here you can find a guide: Creating a Tiledesk Account – Tiledesk help

where is the cloud version? and can i install it with source code?

Multi-project is now available on the Community edition.
You can download it and install