To use any of the above modules you need to generate a key to send texts via Textbelt. To do this, go to textbelt.com and follow the instructions shown on the webpage.
To connect Textbelt to Integromat, follow the general instructions for Connecting to services. After clicking on the Add button, you will be prompted to enter your key generated by Textbelt.
Once you've copied and pasted the key in Integromat, you can continue and finish your scenario.