Click Lock is a function you will find under the Mouse Click features in the Settings panel. You will need to assign it to a button (Pen, Tablet, or Quick Keys), and when you activate it, it will act as a long hold and allow you to grab a chunk of text. When you have highlighted what you want, you will press it again, and then you can copy the text to your clipboard.
It works best when paired with a button set up to Copy (Mac - Command+V and Windows - Ctrl+C).
You will also want to add the application you want to copy from to that Application row and have placed a link below on how to do that. This will be your first step, and then you can set up the Click Lock.
Link to adding applications to the Application row: https://solutions.xencelabs.com/en/support/solutions/articles/67000544218-how-can-i-make-custom-settings-to-a-specific-application-
Setting up and using the Click Lock:
First, you will want to ensure your Xencelabs devices are connected and powered on.
Then you will want to open the Settings pane. The easiest way to do this is to press the top center-left Control button on your Pen Tablet.
 This shows the navigation column, where you navigate to your different connected devices.
 This shows the Device windows. When your Xencelabs devices are powered on and connected, they appear in this window.
 I will use the 3-Button pen to show how to assign the Mouse mode toggle to a pen button.
Select the 3-Button pen.
First, I will set up the Click Lock.
I'm using the bottom button of my pen to assign Click Lock.
 Click on the Bottom Button field, select  Mouse Clicks, and then  select Click Lock.
 This is what Click Lock will look like once you have assigned it to the bottom button of your pen.
Please remember that you can assign it to any button on your Pen Tablet, Pen, or Quick Keys.
Now, let's set up the Save function to the Middle button on your pen.
 This time we are going to click in the field for the Middle button and then  select Keystroke.
 In the Shortcut Name field, give this function a name.
 In the Keystroke Keys field, click in the field, and then press the keys on your keyboard.
Once you press those keys, you will notice they are represented in the field Ctrl+v.
 Click Save, and now you are ready to cut and paste large amounts of text with very little effort.
Making it work" I opened a web page in MS Edge, and then I hovered my pen  at the bottom of the text I wanted to copy and pressed the bottom button on my pen to start the Click Lock.
 I then moved my pen, still hovering over the top of the Pen Tablet, to the top of the text I wanted to copy and pressed the bottom button. This will turn off the Click Lock function.
I then pressed the Middle button on my pen, which copied the highlighted section to the clipboard on my computer.
I can now do Ctrl+v or Command+v and paste the copied text into a document.
Easy ahs fast.