The clipboard can be found on the HTML5 Top menu, with this icon:
Most browsers except older MSIE browsers do not support the direct clipboard reading and writing due to security reasons.
To copy the text from session to clipboard use Ctrl+C and to insert the text from clipboard use Ctrl+V.
But pay attention when you copy the text with Ctrl+C, wait some time before releasing the pushed Ctrl+C buttons, because if the requested clipboard text arrives after you release this key combination, the text will not be added to your environment clipboard. This way uses a native browser clipboard copy support initiated by Ctrl+C.
Alternatively you can use the clipboard menu to copy from and to insert the text into RDP session clipboard.
There you can just insert the text into RDP session clipboard or add it to clipboard and auto-initiate Ctrl+C on RDP session side to insert text. The clipboard menu can be opened via action menu or Shift + F11.
To avoid this behavior set the following line on the Clients folder, by default, the path is: C:\Program Files(x86)\tsplus\Clients\www\software\html5\settings.js :
openonclipblur = false;
If you do not have a file named "settings.js" in the "C:\Program Files (x86)\TSplus\Clients\www\software\html5" folder, then your TSplus version is older and this documentation does not apply. Please update your system first or contact support.