What is the process to generate an E invoice in BUSY? I'm unable to complete it successfully.

To activate & generate E-invoice from BUSY, you need to follow these steps:
Step 1: First you have to create a GSP (GST Suvidha Provider), you need to visit the eway bill or e invoice portal 
Step 2: Then, select Webtel Electrosoft Private Limited and Pinnacle Finserv Advisors Private Limited as the GSP Vendor type.
Step 3: In BUSY, Go to Administration and click on configuration.
Step 4: Select Features / Options and click on GST / VAT, here you will see a option called E-Invoice Required.
Step 5: Set Y to turn it on and mention your place and pincode and GSP userid and password in GSP Configuration tab and save the configuration.
Step 6: Go back to Administration and click on configuration.
Step 7: Choose the Voucher Series Configuration option and select the voucher type for which you want to generate e invoice, such as sales, sales return, etc.
Step 8: Then, select the voucher series and click on Voucher Configuration.
Step 9: Here, you will see options of Input Transport Details, Generate E-Invoice After Saving, set Y to enable that. 
Step 10: Now, create sales invoice and enter all the required details in the transport details window and when you save then voucher you can generate e invoice.