RCTBridgeModule.h file not found

Hi, I have a RN project v0.40.0. I’ve installed Firestack and that recommends I use react-native-oauth. After linking and installing pods, I get the build error, 'RCTBridgeModule.h' file not found in OAuthManager.h.

I have tried replacing,

#import "RCTBridgeModule.h"

with,

#import <React/RCTBridgeModule.h>

Which seems to get rid of the original error but then I get, 'RCTLinkingManager.h' file not found. Doing,

#import <React/RCTLinkingManager.h>

but that results in,

Undefined symbols for architecture i386:
  "_OBJC_CLASS_$_OAuthManager", referenced from:
      objc-class-ref in AppDelegate.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I also tried leaving the #import "RCTLinkingManager.h" as is and added the following search paths as has been suggested on stackoverflow:

$(SRCROOT)/../node_modules/react-native-oauth/ios/OAuthManager
$(SRCROOT)/../node_modules/react-native/Libraries   (recursive)

The first one fixes another error but I got the same Undefined symbols for architecture i386... error, presumably about the #import "RCTLinkingManager.h"

Here is my cocoapods file, in case it helps you spot something:

# Uncomment the next line to define a global platform for your project
# platform :ios, '9.0'

target 'myproject' do
  # Uncomment the next line if you're using Swift or would like to use dynamic frameworks
  # use_frameworks!

  # Pods for myproject

  target 'myprojectTests' do
    inherit! :search_paths
    # Pods for testing
  end

end
source 'https://github.com/CocoaPods/Specs.git'
use_frameworks!
platform :ios, '8.0'

[
  'Firebase',
  'Firebase/Core',
  'Firebase/Auth',
  'Firebase/Storage',
  'Firebase/Database',
  'Firebase/RemoteConfig',
  'Firebase/Messaging'
].each do |lib|
  pod lib
  pod 'DCTAuth', :git => 'https://github.com/danielctull/DCTAuth.git'
end

Note, I’m not very familiar with Cocoapods yet but it kept saying that a podfile already exists and I didn’t know if I should elect to overwrite it or not. I ended up merging the firestack one with this oauth one and added in that DCTAuth line above, hope it’s right. pod install seemed to work but also gave me a yellow warning in my console,

...target overrides the `HEADER_SEARCH_PATHS` build setting defined in `Pods/Target Support Files/Pods-myproject/Pods-myproject.debug.xcconfig'. This can lead to problems with the CocoaPods installation
    - Use the `$(inherited)` flag, or
    - Remove the build settings from the target.

Should I heed this warning?

Thank you