Well, I have achieved this through the UI Form. Actually I have not got the solution to add a category tree in block form. Then I used the UI form and it's worked.
Add this code in your custom UI form.
<argument name="data" xsi:type="array">
<item name="options" xsi:type="object">...
You can Add new group from:
Stores -> Attributes -> Attribute Set
Click on Your attribute set
In the Groups Click Add New . It will create a New Group.
If you want to put it below Content Group, You can drag it using mouse.
In the Screen Shot, I created a Test Group
In your controller file, put this data, make changes according to your needs and code.
path : vendor/addtocart/controller/index/index.php
You can refer following Sites to Configuration Table Rates Shipping Method
Any Query let me know...