If you are not able to downlaod gst return in BUSY for reconcilation,make sure check these steps
1.Make sure gst portal username and gstin is correctly mentioned under GST/VAT tab
2.Then if it show error gst return not filed,check same report on portal,if same not showing on portal,it means it is yet not filed on portal
3.If it is server issue,try downloading after sometime or try by downlaoding manual return
4.Check if there is any permission error,then run BUSY as administartor and then try to download
5.Also check BUSY release update as it should be latest release