Step 1: Sharing BT warehouse Id
The BT warehouse from which inventory is to be synced on Myntra as shown below.
You can get these details from invoicing_companies The warehouse id to be shared with Myntra team. 

Step2: Request for credentials
Once the warehouse Id is shared with Myntra team, they will provide details such as 
Pretr Merchant ID
API Secret Key
Your Username with Pretr/PPMP(Myntra API)
Your Password with Pretr/PPMP(Myntra API)

Step3: Adding Pretr/PPMP(Myntra API) channel
Go to channel setting and add Pretr/PPMP(Myntra API). The above following details shared by Myntra to be added in BT as shown below..


Step4: Generate Auth Token
Added Pretr BTchannel_id shown in the channel settings URL as  along with BT_username to be shared BT Support team to generate H-Hook Key and H-Hook Secret which is to be updated as shown below under channel settings and shared with Myntra team.

Step5: SKU mapping
SKUs listed on Myntra to be mapped in BT via new product or alias (whichever applicable). Also, as there is no listing API for Pretr/PPMP, Offline mapping needs to be done.

Under Inventory--> Manage stock --> Bulk Add Offline Channel SKU

Select Pretr/PPMP channel and Download Current Listing Snapshot, where 5 columns are mandatory as mentioned below.
*Channel Custom Code, Listing ID,Channel Product Ref (mention sku codes)
*Currency INR
*SLA (mandatory which will be specified by the seller)
Fill in the details, select the same channel in the drop-down for which you downloaded the snapshot, append to upload the data. 
- If file fails don't use RETRY option.
- Any new listings created on Myntra need to be mapped via offline mapping.

Step6: Turn ON Inventory sync
Once mapping is complete,add stock if required and  turn ON the inventory sync. Check on Myntra portal whether stock is in sync.

Step7: Place test order on Myntra
The inventory which is in sync, place test order for any sample SKU. Myntra will release/push the same order in BT.

Step 8: Order Processing
The test order to be processed in BT by creating batch, label generation and invoice.  The label and invoice generated for test order to be shred with Myntra.

Additional points:
Return and cancelled order status are saved in BT.

Order Pickups are arrange by Myntra logistics.