Missing jsonwebtoken when declaring PDFServicesSdk

I get the following error when trying to declare PDFServicesSDK const and am unable to proceed past this point. Please help, I've tried everything. 

var PDFServicesSdk = require('./adobe-dc-pdf-services-sdk-node-samples/@adobe/pdfservices-node-sdk');
Uncaught Error: Cannot find module 'jsonwebtoken'

Require stack:
- C:\Program Files\nodejs\adobe-dc-pdf-services-sdk-node-samples\@adobe\pdfservices-node-sdk\src\internal\auth\jwt-authenticator.js
- C:\Program Files\nodejs\adobe-dc-pdf-services-sdk-node-samples\@adobe\pdfservices-node-sdk\src\internal\auth\authenticator-factory.js
- C:\Program Files\nodejs\adobe-dc-pdf-services-sdk-node-samples\@adobe\pdfservices-node-sdk\src\internal\internal-execution-context.js
- C:\Program Files\nodejs\adobe-dc-pdf-services-sdk-node-samples\@adobe\pdfservices-node-sdk\src\execution-context.js
- C:\Program Files\nodejs\adobe-dc-pdf-services-sdk-node-samples\@adobe\pdfservices-node-sdk\src\pdfservices-sdk.js
- <repl>
at Function.Module._resolveFilename (node:internal/modules/cjs/loader:933:15)
at Function.Module._load (node:internal/modules/cjs/loader:778:27)
at Module.require (node:internal/modules/cjs/loader:999:19)
at require (node:internal/modules/cjs/helpers:102:18) {
code: 'MODULE_NOT_FOUND',
requireStack: [
'C:\\Program Files\\nodejs\\adobe-dc-pdf-services-sdk-node-samples\\@adobe\\pdfservices-node-sdk\\src\\internal\\auth\\jwt-authenticator.js',
'C:\\Program Files\\nodejs\\adobe-dc-pdf-services-sdk-node-samples\\@adobe\\pdfservices-node-sdk\\src\\internal\\auth\\authenticator-factory.js',
'C:\\Program Files\\nodejs\\adobe-dc-pdf-services-sdk-node-samples\\@adobe\\pdfservices-node-sdk\\src\\internal\\internal-execution-context.js',
'C:\\Program Files\\nodejs\\adobe-dc-pdf-services-sdk-node-samples\\@adobe\\pdfservices-node-sdk\\src\\execution-context.js',
'C:\\Program Files\\nodejs\\adobe-dc-pdf-services-sdk-node-samples\\@adobe\\pdfservices-node-sdk\\src\\pdfservices-sdk.js',
'<repl>'
]
}
>